Re: [net-next 11/13] igb: Make Tx budget for NAPI user adjustable

Alexander Duyck
2011-09-19T22:26:50Z

On 09/19/2011 02:00 PM, David Miller wrote:
> From: Alexander Duyck<alexander.h.duyck@intel.com>
> Date: Mon, 19 Sep 2011 09:32:18 -0700
>> The fact is ixgbe has been using this parameter this way for over 2
>> years now and the main goal of this patch was just to synchronize how
>> things work on igb and ixgbe.
>>
>> Our hardware doesn't have a mechanism for firing an interrupt after X
>> number of frames so instead we simply have modified things so that we
>> will only process X number of frames and then fire another
>> interrupt/poll if needed. As such we aren't that far out of
>> compliance with the meaning of how this parameter is supposed to be
>> used.
> All I can say is this was a huge mistake you therefore need to revert
> the IXGBE change, these ethtool settings are not for changing NAPI or
> software interrupt behavior.
>
> And if you guys plan to be difficult on this and refuse to remove the
> IXGBE bits, I'm letting you guys know ahead of time that I'll do it
> for you.
>
> If the hardware can't support this facility, neither should these
> ethtool hooks, because the whole point is to avoid hardware interrupts
> from firing using these parameters.
>
> Propose new mechanisms to control NAPI behavior if you want.
I'll remove the ixgbe code if that is what you want. It may be a month
or so before I can get to it though since I am slammed with work so if
you are in a hurry for it you might want to work with Jeff Kirsher to
have the code removed.

As far as this current patch goes I honestly don't have the time to add
or rewrite yet another ethtool interface so I will probably just see
about dropping the ethtool portion of this patch and update the
description in order to make it acceptable.

Thanks,

Alex